Perrubo wants to buy it for one gold coin, why, if I were desperate for food and water like my companions at Blackhearth, I might be tempted to take him up on it!
I do believe they should be marked "Plot" however! <3
He buys cheap, sells high.
The Concave key is also sellable for 1 gp, tested with Higgins.
Aberdenn as well.